Final answer:
Frederick Douglass was a convincing spokesperson for the cause of abolition because of his personal experience as a former slave and his powerful oratory skills.
Step-by-step explanation:
Frederick Douglass was a convincing spokesperson for the cause of abolition because of his personal experience as a former slave. After escaping from slavery, Douglass became a gifted orator and a powerful narrator of his experiences, captivating his listeners with his commanding presence and powerful speaking skills.
His autobiography, Narrative of the Life of Frederick Douglass, An American Slave Written by Himself, was widely read and translated into several languages, making him one of the most famous and influential voices in the abolitionist movement.